1. Field of the Invention
The present invention relates to powered and non-powered air mattresses primarily intended for hospitals, long-term care facilities and in-home use. Such air mattresses are designed to prevent or limit the creation of ulcers on the body of the patient during long periods of lying on the mattress.
2. Description of the Related Art
There have been air mattresses made for use in long-term care facilities and hospitals having air cylinders. U.S. Pat. No. 5,634,224 to Gates describes a cushioning device comprising an envelope containing a fluid in which the envelope has a pressure relief valve and an intake valve to regulate the deformation of the envelope under the load and reformation of the envelope when the load is removed. U.S. Pat. No. 6,223,369 to Maier describes patient support surfaces that use different arrangements of air cylinders and static or dynamic performance thereof, either non-powered or powered. At external valving arrangement for a static non-powered embodiment permits practice of a “recharging” technique using an air pump and self-calibrated valve, to return the air pressure in static air cylinders to their original manufactured specifications.